Speech recognition method and speech recognition apparatus
First Claim
1. A speech recognition method of recognizing an input speech in a noisy environment by using a plurality of clean speech models, each of said clean speech models having a clean speech feature parameter S representing a cepstrum parameter of a clean speech thereof, said speech recognition method comprising the processes of:
- detecting a noise feature parameter N representing a cepstrum parameter of a noise in said noisy environment, immediately before said input speech is input;
detecting an input speech feature parameter X representing a cepstrum parameter of said input speech in said noisy environment;
calculating a modified clean speech feature parameter Y according to a following equation;
space="preserve" listing-type="equation">Y=k·
S+(1-k)·
N (0<
k≦
1),where said "k" is a predetermined value corresponding to a signal-to-noise ratio in said noise environment;
comparing said input speech feature parameter X with said modified clean speech feature parameter Y; and
recognizing said input speech by repeatedly carrying out said calculating process and said comparing process, respectively, with respect to said plurality of clean speech models.
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Abstract
A speech recognition method of recognizing an input speech in a noisy environment by using a plurality of clean speech models is provided. Each of the clean speech models has a clean speech feature parameter S representing a cepstrum parameter of a clean speech thereof. The speech recognition method has the processes of: detecting a noise feature parameter N representing a cepstrum parameter of a noise in the noisy environment, immediately before the input speech is input; detecting an input speech feature parameter X representing a cepstrum parameter of the input speech in the noisy environment; calculating a modified clean speech feature parameter Y according to a following equation:
Y=k·S+(1-k)·N (0<k≦1),
where the "k" is a predetermined value corresponding to a signal-to-noise ratio in the noise environment; comparing the input speech feature parameter X with the modified clean speech feature parameter Y; and recognizing the input speech by repeatedly carrying out the calculating process and the comparing process with respect to the plurality of clean speech models.
112 Citations
12 Claims
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1. A speech recognition method of recognizing an input speech in a noisy environment by using a plurality of clean speech models, each of said clean speech models having a clean speech feature parameter S representing a cepstrum parameter of a clean speech thereof, said speech recognition method comprising the processes of:
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detecting a noise feature parameter N representing a cepstrum parameter of a noise in said noisy environment, immediately before said input speech is input; detecting an input speech feature parameter X representing a cepstrum parameter of said input speech in said noisy environment; calculating a modified clean speech feature parameter Y according to a following equation;
space="preserve" listing-type="equation">Y=k·
S+(1-k)·
N (0<
k≦
1),where said "k" is a predetermined value corresponding to a signal-to-noise ratio in said noise environment; comparing said input speech feature parameter X with said modified clean speech feature parameter Y; and recognizing said input speech by repeatedly carrying out said calculating process and said comparing process, respectively, with respect to said plurality of clean speech models. - View Dependent Claims (2)
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3. A speech recognition method of recognizing an input speech in a noisy environment by using a plurality of clean speech models, each of said clean speech models having a clean speech feature parameter S representing a cepstrum parameter of a clean speech thereof, said speech recognition method comprising the processes of:
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detecting a noise feature parameter N representing a cepstrum parameter of a noise in said noisy environment, immediately before said input speech is input; detecting an input speech feature parameter X representing a cepstrum parameter of said input speech in said noisy environment; calculating a modified input speech feature parameter Z according to a following equation;
space="preserve" listing-type="equation">Z={X-(1-k)·
N}/k (0<
k≦
1),where said "k" is a predetermined value corresponding to a signal-to-noise ratio in said noise environment; comparing said modified input speech feature parameter Z with said clean speech feature parameter S; and recognizing said input speech by repeatedly carrying out said calculating process and said comparing process, respectively, with respect to said plurality of clean speech models. - View Dependent Claims (4)
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5. A speech recognition apparatus for recognizing an input speech in a noisy environment by using a plurality of clean speech models, each of said clean speech models having a clean speech feature parameter S representing a cepstrum parameter of a clean speech thereof, said speech recognition apparatus comprising:
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a first detecting device for detecting a noise feature parameter N representing a cepstrum parameter of a noise in said noisy environment, immediately before said input speech is input; a second detecting device for detecting an input speech feature parameter X representing a cepstrum parameter of said input speech in said noisy environment; a calculating device for calculating a modified clean speech feature parameter Y according to a following equation;
space="preserve" listing-type="equation">Y=k·
S+(1-k)·
N (0<
k≦
1),where said "k" is a predetermined value corresponding to a signal-to-noise ratio in said noise environment; and a comparing device for comparing said input speech feature parameter X with said modified clean speech feature parameter Y in order to recognize said input speech. - View Dependent Claims (6)
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7. A speech recognition apparatus for recognizing an input speech in a noisy environment by using a plurality of clean speech models, each of said clean speech models having a clean speech feature parameter S representing a cepstrum parameter of a clean speech thereof, said speech recognition apparatus comprising:
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a first detecting device for detecting a noise feature parameter N representing a cepstrum parameter of a noise in said noisy environment, immediately before said input speech is input; a second detecting device for detecting an input speech feature parameter X representing a cepstrum parameter of said input speech in said noisy environment; a calculating device for calculating a modified input speech feature parameter Z according to a following equation;
space="preserve" listing-type="equation">Z={X-(1-k)·
N}/k (0<
k≦
1),where said "k" is a predetermined value corresponding to a signal-to-noise ratio in said noise environment; and a comparing device for comparing said modified input speech feature parameter Z with said clean speech feature parameter S in order to recognize said input speech. - View Dependent Claims (8)
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9. A program storage device readable by a speech recognition apparatus tangibly embodying a program of instruction executable by said speech recognition apparatus to perform method processes for recognizing an input speech in a noisy environment by using a plurality of clean speech models, each of said clean speech models having a clean speech feature parameter S representing a cepstrum parameter of a clean speech thereof, said method processes comprising:
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detecting a noise feature parameter N representing a cepstrum parameter of a noise in said noisy environment, immediately before said input speech is input; detecting an input speech feature parameter X representing a cepstrum parameter of said input speech in said noisy environment; calculating a modified clean speech feature parameter Y according to a following equation;
space="preserve" listing-type="equation">Y=k·
S+(1-k)·
N (0<
k≦
1),where said "k" is a predetermined value corresponding to a signal-to-noise ratio in said noise environment; comparing said input speech feature parameter X with said modified clean speech feature parameter Y; and recognizing said input speech by repeatedly carrying out said calculating process and said comparing process, respectively, with respect to said plurality of clean speech models. - View Dependent Claims (10)
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11. A program storage device readable by a speech recognition apparatus tangibly embodying a program of instruction executable by said speech recognition apparatus to perform method processes for recognizing an input speech in a noisy environment by using a plurality of clean speech models, each of said clean speech models having a clean speech feature parameter S representing a cepstrum parameter of a clean speech thereof, said method processes comprising:
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detecting a noise feature parameter N representing a cepstrum parameter of a noise in said noisy environment, immediately before said input speech is input; detecting an input speech feature parameter X representing a cepstrum parameter of said input speech in said noisy environment; calculating a modified input speech feature parameter Z according to a following equation;
space="preserve" listing-type="equation">Z={X-(1-k)·
N}/k (0<
k≦
1),where said "k" is a predetermined value corresponding to a signal-to-noise ratio in said noise environment; comparing said modified input speech feature parameter Z with said clean speech feature parameter S; and recognizing said input speech by repeatedly carrying out said calculating process and said comparing process, respectively, with respect to said plurality of clean speech models. - View Dependent Claims (12)
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Specification